Potato problems - black speckles on leaves, yellowing and dying
I started noticing some tiny black spots on my potato vine leaves but didn't think much of it because they were still pretty green and looked alright otherwise. Now the branches(?) are turning yellow and dying off over the course of a couple days. Is this characteristic of a fungus? Perhaps a nutrient deficiency? I've included some pics of the problem below.
Pardon the fogginess... I ran from the nice a/c inside into the humidity outside before work to snap these, and bam! insta-fog. Didn't realize it until I uploaded them.
Bonus points to anybody who can offer some suggestions about why the cos lettuce in the upper right hand side of one of the pics has been roughly 1" tall for about a month now. (brand new gardener here slowly learning!)